The overall objective of the investigators is to apply both classic and new measures of vestibular function to the study of Meniere's disease (MD). These measures would enable earlier diagnosis which, in turn, could lead to better treatment response. These methods have the potential to provide a superior means of monitoring the course of the disease and its response to therapy. Finally, these vestibular function measures may provide new insights into the pathophysiology of MD symptoms since they are based upon the physiology of specific parts of the vestibular end-organs. To accomplish these goals, this project will apply vestibular function tests to three groups of subjects: normal controls, subjects with total unilateral vestibular hypofunction (UVH) after acoustic neuroma removal, and MD subjects who, by the nature of their disease, have partial UVH. The three specific aims of this grant are: 1) Characterize the temporal relationship between acute vertigo attacks and long-term loss of vestibular function in MD subjects by correlating results of serial vestibular test batteries with clinical vestibular symptom status; 2) Test the hypothesis that otolith organ dysfunction is an early and consistent finding in MD by applying two new tests of otolith function, positional optokinetic afternystagmus (pOKAN) and vestibular evoked myogenic potentials (VEMP); and 3) Lay the groundwork for detailed clinicopathological studies of the correlation between vestibular function tests and temporal bone vestibular otopathology by soliciting enrollment of study subjects as future temporal bone donors to the NIDCD National Temporal Bone, Hearing and Balance Pathology Resource Registry.